I've gotten the recommendation in the past of switching to glass pitchers instead to avoid the "sticks to the inside of the plastic pitcher" issue.
The Soylent pitcher is just a rebranded Takeya 2L pitcher you can get off Amazon if you want it faster, FWIW.
Rich Chocolate and the PB Chocolate are the only two I use. Also, if you want more taste use less water, sure it'll be thicker but look at how much powder you are using and think about how much of that is vitamins/minerals/electrolytes/protein and how little of it is flavoring.
I put a few fingers of water in a 2-quart Takeya pitcher then put in my heavy whipping cream, then my mct, then my powder. I'll then only fill the pitcher up about 75% and that's my day's worth of Keto Chow. You can get by with less water but then the air gets behind the fluid and shoves it through the threading and gaskets when you shake it heh.
We use the Smuggler's Cove coconut cream recipe and it was fine. We batch in water-tight pitchers so it's easy to give them a good shake if needed.
https://www.amazon.com/gp/product/B00DCYNP2G/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1
These are Soylent bottles.
You can still buy them on amazon: https://www.amazon.com/Takeya-Blueberry-Patented-Airtight-Pitcher/dp/B00DCYNP2G/
I drink lemon water. I take a lemon, roll it around to loosen up the inside, and quarter it length-wise.
I fill up a Takeya 2 quart pitcher most of the way with water and then squeeze the lemon quarters into it, and then drop the rinds in.
It gets a bunch of floaty goodness in there and tastes great.
Try making what i call 'tea water' too, which is simultaneously a lazy person's iced tea and actually surprisingly good. It's cold brew tea, so just toss some tea bags in some room temp water and throw the whole thing in the fridge for a while.
I usually take one of my pitchers (amazon link, although costco has a better price if you can find it there), fill it up to the top, put in two jasmine tea bags, and leave it for 12 hours in the fridge for a lightly jasmine'd flavored water. If the tea gets too concentrated for your taste then you can just mix in more water! Add more tea bags and/or time for a more serious iced tea.
If I don't do that with cheapo $3 for 100 tea bags though (Asian markets!!!!) I usually drink really high quality loose leaf tea. I'll either use a teapot/mug for one or a gaiwan and bring the water kettle over to my desk and just keep on making more infusions of the tea with a timer. Having the brewing device next to me or even straight up being the drinking device too makes it a lot easier for me not to forget about the tea, and it means I won't reach for sugary drinks too :)
You can buy the exact same pitcher from Amazon, however:
The original soylent pitcher was the Takeya 2L. However any 2L will do, like this Rubbermaid.
The Amazon product page lists the dimensions as 6.1 x 4.1 x 12.2 in. My tape measure agrees.
Anything you can seal up and shake works well. I use one of those shakers you mentioned. Some people like glass jars. If you're interested in pitchers that can mix the whole bag at once the same pitcher sold by Soylent is available elsewhere. Here are some previous threads about the topic as well.
One 500 calorie meal is 106 grams of powder (1/4 pouch). Approximately 112 ml or 1/2 cup by volume.